Heterostructures of Perovskite Type Materials for Electronic Application

Aim of the presented project is a basic investigation on heterostructures of bariumtitanate BaTiO 3 and perovskite type lanthanum-nickel-cobaltite LaN 1-x Cox O3 in thick film and thin film technique. Bariumtitanate is a widely used ferroelectric material for ceramic multilayer capacitors. The homologous series of LaNi1-x Cox O3 is a good electronic conductor, tunable with x from p- to n-type conduction. Technological application as electrode material for BaTiO3 -based capacitors is hindered by the inhibition of densification of sintered devices and the deterioration of electrical properties of the electrode material. These effects might be due to chemical, mechanical, electronic or transport problems. To enlighten the complex phenomenology of co-firing and to distinguish between influences from green-body processing and processes at sintering temperature, a microstructural and microanalytical investigation should be carried out with carefully prepared ceramic specimen. A comparison to heterostructures made by Chemical Solution Deposition (CSD) should reveal differences with respect to materials interaction as well as electrical function. The CSD-process is carried out at significantly lower temperatures, which influences the electronic properties mainly through microstructure and defect distribution. To make use of the optimum in experience and equipment the project should be carried out with two research institutions. The preparation and investigation of the thick film heterostructures should be done at the Ceramic Department of "Josef Stefan" Institute, LjubIjana, because of the great experience in the field of electroceramics and the concentration of excellent equipment for ceramic processing and characterisation. For the studies on thin film heterostructures the Institut für Werkstoffe der Elektrotechnik, RWTH Aachen, offers the ideal equipment for preparation and characterisation of CSD thin films. The research activities of the last years have been focused on ferroelectric and magnetoresistive thin films and their application in semiconductor technology.